The fabric of our universe is spacetime, which consists of the three spatial dimensions (length, width and height) combined with the dimension of time. Imagine this fabric as a stretchy, rubber sheet. And then imagine placing a giant bowling ball on that sheet. The sheet would warp around the bowling ball, and any object placed near the bowling ball would roll toward it. This metaphor for Albert Einstein's theory of general relativity explains how gravity works. (Despite being Einstein's greatest achievement, general relativity is not for what he won the Nobel Prize; instead, the prize was awarded for his work on the photoelectric effect.)

But this wasn't Einstein's only contribution. He also came up with special relativity which describes how time slows down for moving objects, especially as they travel closer to the speed of light.

Interestingly, the effects of both general and special relativity must be taken into account for GPS satellites to work properly. If these effects were not considered, then the clocks on Earth and on the satellites would be out of sync, and consequently, the distances reported by the GPS unit would be wildly inaccurate. So, every time you use your smartphone to succesfully find the local Starbucks, give thanks to Albert Einstein.

Source: Galileo's Finger: The Ten Great Ideas of Science by Peter Atkins